has anyone else experience this.....

As usual Al is correct, although many sellers claim that they are selling NOS tubes which are actually used.

regardless, them turning lean after a short time of use is what im worried about. I talked back to who I brought them from and he informed me they were used nos tubes, I put back in a pair of Phillips/miniwatt Holland I had in before and the sound was fine again...........

There is something wrong with the tubes, (they might just be
worn out? How used is used?) or your cj PV-10 just doesn't
play well with them or you just don't like them. Maybe time
to move on.

Sorry, but what you describe, isn't what I have found to be
true with NOS Mullards. I have been using these tubes for
over 30 years and still have bunches of them left. By far
"my" favorite tube, but definitely not for
everyone. As always, YMMV...

that's what I think as well, actually they blew out my preamp, repair guy said it blew a resistor, was pulling 6amps which it should not have.............